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Message-Id: <20251125-reset-gpio-add-devlink-v1-1-a1909fef227b@linaro.org>
Date: Tue, 25 Nov 2025 13:55:35 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Philipp Zabel <p.zabel@...gutronix.de>,
Krzysztof Kozlowski <krzk@...nel.org>, Val Packett <val@...kett.cool>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH] reset: gpio: add a devlink between reset-gpio and its
consumer
From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
The device that requests the reset control managed by the reset-gpio
device is effectively its consumer but the devlink is only established
between it and the GPIO controller exposing the reset pin. Add a devlink
between the consumer of the reset control and its supplier. This will
allow us to simplify the GPIOLIB code managing shared GPIOs when
handling the corner case of reset-gpio and gpiolib-shared interacting.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
This change will allow us to simplify the code in gpiolib-shared.c in
the next cycle, so it would be awesome if it could make v6.19.
Val: I'm Cc'ing you as you're already playing with audio on hamoa. If v2
of the reset-gpios fix works for you, could you please also test this
and make sure it doesn't break anything with soundwire?
Thanks in advance,
Bart
---
drivers/reset/core.c | 73 +++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 58 insertions(+), 15 deletions(-)
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index 0135dd0ae20498396fdb5a682f913b6048cb5750..15b8da9ebcf196f7d5ce7921e4f8aba0ea6b0de4 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -20,6 +20,7 @@
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/of.h>
+#include <linux/of_platform.h>
#include <linux/reset.h>
#include <linux/reset-controller.h>
#include <linux/slab.h>
@@ -82,6 +83,7 @@ struct reset_gpio_lookup {
struct of_phandle_args of_args;
struct fwnode_handle *swnode;
struct list_head list;
+ struct auxiliary_device *adev;
};
static const char *rcdev_name(struct reset_controller_dev *rcdev)
@@ -829,16 +831,16 @@ static void reset_gpio_aux_device_release(struct device *dev)
kfree(adev);
}
-static int reset_add_gpio_aux_device(struct device *parent,
- struct fwnode_handle *swnode,
- int id, void *pdata)
+static struct auxiliary_device *
+reset_add_gpio_aux_device(struct device *parent, struct fwnode_handle *swnode,
+ int id, void *pdata)
{
struct auxiliary_device *adev;
int ret;
adev = kzalloc(sizeof(*adev), GFP_KERNEL);
if (!adev)
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);
adev->id = id;
adev->name = "gpio";
@@ -850,23 +852,55 @@ static int reset_add_gpio_aux_device(struct device *parent,
ret = auxiliary_device_init(adev);
if (ret) {
kfree(adev);
- return ret;
+ return ERR_PTR(ret);
}
ret = __auxiliary_device_add(adev, "reset");
if (ret) {
auxiliary_device_uninit(adev);
kfree(adev);
- return ret;
+ return ERR_PTR(ret);
}
- return ret;
+ return adev;
+}
+
+static void reset_gpio_add_devlink(struct device_node *np,
+ struct reset_gpio_lookup *rgpio_dev)
+{
+ struct device *consumer;
+
+ /*
+ * We must use get_dev_from_fwnode() and not of_find_device_by_node()
+ * because the latter only considers the platform bus while we want to
+ * get consumers of any kind that can be associated with firmware
+ * nodes: auxiliary, soundwire, etc.
+ */
+ consumer = get_dev_from_fwnode(of_fwnode_handle(np));
+ if (consumer) {
+ if (!device_link_add(consumer, &rgpio_dev->adev->dev, DL_FLAG_STATELESS))
+ pr_warn("Failed to create a device link between reset-gpio and its consumer");
+
+ put_device(consumer);
+ }
+ /*
+ * else { }
+ *
+ * TODO: If ever there's a case where we need to support shared
+ * reset-gpios retrieved from a device node for which there's no
+ * device present yet, this is where we'd set up a notifier waiting
+ * for the device to appear in the system. This would be a lot of code
+ * that would go unused for now so let's cross that bridge when and if
+ * we get there.
+ */
}
/*
- * @args: phandle to the GPIO provider with all the args like GPIO number
+ * @np: OF-node associated with the consumer
+ * @args: phandle to the GPIO provider with all the args like GPIO number
*/
-static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
+static int __reset_add_reset_gpio_device(struct device_node *np,
+ const struct of_phandle_args *args)
{
struct property_entry properties[2] = { };
unsigned int offset, of_flags, lflags;
@@ -916,8 +950,14 @@ static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
list_for_each_entry(rgpio_dev, &reset_gpio_lookup_list, list) {
if (args->np == rgpio_dev->of_args.np) {
- if (of_phandle_args_equal(args, &rgpio_dev->of_args))
- return 0; /* Already on the list, done */
+ if (of_phandle_args_equal(args, &rgpio_dev->of_args)) {
+ /*
+ * Already on the list, create the device link
+ * and stop here.
+ */
+ reset_gpio_add_devlink(np, rgpio_dev);
+ return 0;
+ }
}
}
@@ -950,11 +990,14 @@ static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
goto err_put_of_node;
}
- ret = reset_add_gpio_aux_device(parent, rgpio_dev->swnode, id,
- &rgpio_dev->of_args);
- if (ret)
+ rgpio_dev->adev = reset_add_gpio_aux_device(parent, rgpio_dev->swnode,
+ id, &rgpio_dev->of_args);
+ if (IS_ERR(rgpio_dev->adev)) {
+ ret = PTR_ERR(rgpio_dev->adev);
goto err_del_swnode;
+ }
+ reset_gpio_add_devlink(np, rgpio_dev);
list_add(&rgpio_dev->list, &reset_gpio_lookup_list);
return 0;
@@ -1034,7 +1077,7 @@ __of_reset_control_get(struct device_node *node, const char *id, int index,
gpio_fallback = true;
- ret = __reset_add_reset_gpio_device(&args);
+ ret = __reset_add_reset_gpio_device(node, &args);
if (ret) {
rstc = ERR_PTR(ret);
goto out_put;
---
base-commit: 0067c9346f8746a9d9ddc15ffc0ddf7545d318e6
change-id: 20251125-reset-gpio-add-devlink-8fe5b958d699
Best regards,
--
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
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